Reported herein is a practical and selective assembly of novel isoquinolone-containing spirocyclic and oxepine-fused polycyclic skeletons through a rhodium(III)-catalyzed oxidative [4+1] spiroannulation or formal [4+3] annulation reactions of diverse NH-isoquinolones...

An efficient strategy for the preparation of spirocyclic indole-N-oxide compounds through a Rh(III)-catalyzed [4 + 1] spiroannulation reaction of N-aryl nitrones with 2-diazo-1,3-indandiones as C1 synthons under extremely mild conditions is presented. From this reaction, 40 spirocyclic indole-N-oxides were easily obtained in up to 98% yield. In addition, the title compounds could be successfully used for the construction of structurally intriguing maleimide-containing fused polycyclic scaffolds via a diastereoselective 1,3-dipolar cycloaddition reaction with maleimides.